I was always asked by classical musicians how is it that I do not read music while playing different composition of music. I have now played the piano for about 9 years and over and can say that now my techniques and understanding and ear training have paid off and can say I can play almost any piece of music only by listening to the piece once or twice.
For some musicians and vocalist such as Stevie wonder playing by ear for them has become a natural skills which they have perfected and have being gifted with. Though for some including myself, are not so much ear trained or gifted in that sense hours of ear training chords composition had to be implemented in order to better understand and grasp the idea behind it.
A number of people do you still read music? I say do I need to? It's being fantastic experience and I am still learning how to perfect my craft even now!
I now share my knowledge and experience on my youtube channel: onecliptv where anyone wanting to learn how to play by ear can do so at home and for free.